Backlight upper left corner

Hi,

I recently replaced my screen (backlight, touch, etc)and after few days the upper left corner of backlight stopped working. I powered phone off then on and then backlight worked perfectly for an hour. It happens every time I power off then on my IPhone. Could it be that I didn’t connect properly the flex cable ?

IPhone 6s Plus

Thanks in advance!

Thank very much for reply.

I checked if it is not properly connected and it looked connected properly. But, when I turn phone on the flex cable for backlight gets really hot while screen is on. As I suspected, there is a short circuit at very connection and phone cuts current through hot parts. I will order another screen with backlight and test if it is on flex cable or board.